Bio III Exam (ch. 40, 41, 42, 45, 48)

Water balance (40)

an important component of homeostasis (maintenance of constant and favorable conditions in cells and tissues)

an animal achieves this when its water intake equals its water loss

it’s intimately associated w/ sustaining balanced concentrations of electrolytes throughout body

Electrolyte (40)

a compound that dissociates into ions when dissolved in water

they conduct electrical current (where name stems from)

Osmosis (40)

water enters and leaves cells by this process (water diffusion)

occurs only when solutions are separated by a membrane that permits water to cross but selectively holds back some or all solutes

Osmolarity (40)

the solute concentration of a solution

if the solutes are separated by a selectively permeable membrane and cannot cross that membrane, waters moves from the side of lower solute concentration to higher solute concentration

Isosmotic (40)

when the movement of water is equal in both directions

seawater is an example of this with the tissues of osmoconforming animals

Hyposmotic (40)

lower solute concentration

higher free H₂O concentration

if two solutions differ in osmolarity, the net flow of water is from the less concentrated solution or ________ solution

Hyperosmotic (40)

higher solute concentration

lower free H₂O concentration

if two solutions differ in osmolarity, the net flow of water is from the more concentrated solution or ________ solution

Osmotic stress (40)

occurs when the concentration of dissolved substances in a cell or tissue is abnormal

• meaning that water and solute concentrations are different from their set points

can be caused by loss or gain of water or electrolytes to or from animal’s environment

Osmoregulation (40)

how organisms respond to osmotic stress

the process by which organisms control the concentrations of water and solutes in their bodies

this is required in marine vertebrates b/c seawater is hyperosmotic to their tissues

Osmoconformers (40)

an animal whose tissue osmolarity is isosmotic to its environment

do not regulate their osmolarity

live in water that has a stable composition

some marine animals (typically invertebrates)

e.g., sharks, rays, and akates

Osmoconformer: sharks (40)

animal whose tissue osmolarity is isosmotic to its environment

shark blood:

• contains low concentrations of ions; high concentration of urea

• this increases blood osmolarity so that it’s nearly isosmotic w/ seawater

• requires energy expenditure to protect them from toxic effects of high urea concentrations

result:

• they lose little water by osmosis

although they’re osmoconformers, they still maintain a relatively low concentration of salt (NaCl) in their blood

• they secrete salt through their rectal gland

Osmoregulators (40)

an animal that actively regulates the osmolarity of its tissues

• they must expend energy to maintain osmotic gradients (to control water uptake and loss in a hyperosmotic or hyposmotic environment)

e.g., marine and freshwater bony fishes and terrestrial animals

Energetics of osmoregulation (40)

osmoregulators must expend energy to maintain osmotic gradients

the amount of energy differs based on:

• how different the animal’s osmolarity is from its surroundings

• how easily water and solutes move across the animal’s surface

• work required to pump solutes across the membrane

Transport epithelia (40)

specialized for moving solutes in specific directions

• typically arranged in complex networks

Ammonia (40)

a form of nitrogenous waste

it’s toxic to cells b/c at high concentrations it raises the pH of intracellular and extracellular fluids enough to inactivate enzymes

• some animals convert this to less toxic compounds prior to excretion

high solubility in water

high amount of water required for excretion

high toxicity

groups where it’s the primary waste:

• most bony fishes, aquatic invertebrates

method of synthesis:

• product of breakdown of amino acids and nucleic acids

low energy cost of synthesis

method of excretion:

• in urine, and diffuses across gills

Nitrogenous wastes (40)

compounds excreted by animals to rid their bodies of excess nitrogen

main types:

1. ammonia

2. urea

3. uric acid

Urea (40)

a form of nitrogenous waste

medium solubility in water

medium amount of water required for excretion

medium toxicity

groups where it’s the primary waste:

• mammals, most adult amphibians, sharks, rays, skates

method of synthesis:

• synthesized in liver, starting w/ ammonia or amino groups from amino acids

high energy cost of synthesis

method of excretion:

• in urine (mammals); diffuses across gills (sharks)

also involved in creating steep osmotic gradient in space surrounding nephron

• concentration of this is high in inner medulla and low in outer medulla b/c the innermost section of collecting duct is permeable to this

Uric acid (40)

a form of nitrogenous waste

very low solubility in water

very low amount of water required for excretion

low toxicity

groups where it’s the primary waste:

• birds and other reptiles, most terrestrial arthropods (insects, spiders)

method of synthesis:

• synthesis starts w/ nucleic acids

high energy cost of synthesis

method of excretion:

• with feces

Rectal gland (40)

organ that secretes a concentrated salt solution into it's rectum, where it’s then excreted into environment

• early experiments showed that normal salt excretion occurred only if solution in this organ contained ATP (supported hypothesis that salt excretion involves active transport)

Molecular model for salt excretion (40)

salt excretion in sharks is a multistep process, summarized:

1. Na⁺/K⁺-ATPase pumps Na⁺ out of epithelial cells across basolateral surface, into interstitial fluid (extracellular fluid surrounding rectal gland)

   1. the pump also moves K⁺ into the cell from interstitial fluid, creating electrochemical gradient that favors diffusion of Na⁺ into cell and K⁺ out of cell

2. Na⁺/Cl^-/K⁺ cotransporter moves these 3 ions into cell by secondary active transport, powered by Na⁺ gradient

   1. this cotransporter allows sodium ions to diffuse into cell down electrochemical gradient, causing Cl^- and K⁺ to move into cell against their electrochemical gradients

3. as Cl^- builds up inside cell, it diffuses down its electrochemical gradient out of cell and into lumen of gland thru chloride channel located in apical membrane

   1. at the same time, potassium diffuses out of cell into interstitial fluid thru basolateral potassium channels

4. following its electrochemical gradient, sodium diffuses from interstitial fluid into lumen of gland thru spaces b/w cells

How freshwater fishes osmoregulate (40)

freshwater fishes lose electrolytes across their gill epithelium by diffusion

• to maintain homeostasis, they have to actively transport ions back into body across gill epithelium

sea bass & salmon:

• sea bass & several salmon species move b/w salt water & freshwater

  • they move b/w environments w/ dramatically different osmotic stresses

• marine bony fishes have specialized cells, called chloride cells

  • when sea bass & salmon are in salt water, these cells are abundant and active

Chloride cells (40)

specialized cells in gill epithelium of marine (saltwater) bony fishes

• move salt using combination of membrane proteins used by epithelial cells in shark rectal gland

recent research suggest there’s a freshwater version of this cell that imports salt

• osmoregulatory cells may be in different locations

• different forms of Na⁺/K⁺-ATPase may be activated

• orientation of a key transport protein “flips”

Chloride cells: freshwater (40)

evidence for existence of this cell:

1. osmoregulatory cells may be in different locations

   1. salmon taken from freshwater and seawater have chloride cells in different locations on the gills (same is true for other species that switch b/w freshwater & saltwater)

   2. suggests that when nature of the osmotic stress changes, the structure of the gill epithelium changes

2. different forms of Na⁺/K⁺-ATPase may be activated

   1. salmon genome contains genes for different forms of Na⁺/K⁺-ATPase

   2. form used in seawater differs from form used in freshwater

3. orientation of a key transport protein “flips”

   1. when fish are in seawater, the protein (cotransporter) is located on basolateral side of chloride cells

   2. in freshwater, the protein (cotransporter) is on apical side of chloride cell

Water and electrolyte balance in insects (40)

insects cope w/ their desert environment in two ways:

1. minimizing water loss from body surface

   1. their exoskeleton consists of chitin, tough polysaccharide and layers of protein = cuticle

2. carefully regulating amount of water and electrolytes they excrete

Cuticle (40)

terrestrial insects’ exoskeleton consisting of chitin (tough polysaccharide) and layers of protein

this is covered w/ layer of waterproof wax, and adaptation to minimize evaporative water loss

Hemolymph (40)

blood-like fluid found in insects

pumped by the heart and transports electrolytes, nutrients, and waste products

modified in a regulated process to produce urine

insects regulate this to maintain homeostasis

Malpighian tubules (40)

excretory organs found insects to maintain water and electrolyte balance

these organs have a large surface area

in direct contact with the hemolymph and empty into hindgut

these organs are also responsible for forming a filtrate, a filtered liquid, from the hemolymph

• this “pre-urine” then passes into the hindgut, where it's processed and modified before excretion

Hindgut (40)

posterior portion of insects digestive tract that helped to maintain water and electrolyte balance

“pre-urine” passes into this portion where it's processed and modified before excretion

How insects make concentrated urine (40)

epithelial cells in malpighian tubules contain pumps that actively transport potassium ions into lumen of the organ

• high concentration of potassium ion brings water into tubules by osmosis

• other electrolytes and nitrogenous waste than diffuse into the filtrate

filtrate that accumulates inside the mouth and tubules flow into the hindgut, where it joins digested food

if an insect is osmotically stressed, electrolytes and water from the filtrate are reabsorbed from the hindgut and return to the hemolymph, while uric acid remains in the hindgut

• absorption results information of hyper osmotic final urine, conservation of water, and efficient elimination of nitrogenous waste

Water and electrolyte balance industrial vertebrates (40)

the process of maintaining stable water and ion concentration in land dwelling vertebrates

prevents dehydration while maintaining homeostasis

the kidneys are the primary organs responsible for osmoregulation and nitrogenous waste removal

water is replaced primarily by drinking; electrolytes replaced through food

Kidney (40)

the primary Osmoregulatory organ of terrestrial vertebrates

Function:

• Regulates water balance

• Regulates electrolyte balance

• Removes nitrogenous waste

• Produces urine

Maintains internal homeostasis despite changes in the external environment

Nephron (40)

basic functional unit of the kidney; most of the kidneys masses made up of these small structures

the work involved in maintaining water and electrolyte balance occurs here

these are located almost entirely in the outer region of the organ (cortex), some extend from cortex into kidney’s inner region (medulla)

function:

• filters blood

• reabsorbs useful substances

• secretes wastes

• forms urine

four major regions of this unit:

1. renal corpuscle

2. proximal tubule

3. loop of Henle

4. distal tubule

5. collecting duct (they empty into here)

Renal corpuscle (40)

one of the major regions of the nephron

urine formation begins here

filters blood, forming a filtrate, or pre-urine, consisting of ions, nutrients, waste, and water

structure of this allows it to function as filtration device:

• water and solutes forced from the blood and pass thru pores into Bowman’s capsule

structure & function:

• forms a capsule that encloses a cluster of tiny blood vessels, or capillaries (glomerulus)

• these vessels bring blood to nephron from renal artery

• the glomerulus & Bowman’s capsule make up this region

can produce abt 180L of filtrate per day

Glomerulus (40)

found in the renal corpuscle

• forms a capsule that encloses this

ball-like cluster of capillaries surrounded by Bowman’s capsule

Bowman’s capsule (40)

found in the renal corpuscle

• this & the glomerulus make up the renal corpuscle

region of nephron that surrounds the glomerulus

Proximal tubule (40)

one of the major regions of the nephron

has epithelial cells that reabsorb nutrients, ions, and water from the filtrate into the blood

filtrate inside this contains water and small solutes such as urea, glucose, amino acids, vitamins, electrolytes

• some are waste; others are valuable nutrients

the epithelial cells of this region contain microvilli facing the lumen

• microvilli increase the surface area

Proximal tubule: selective reabsorption (40)

model of molecular mechanisms involved in this process

1. active transport creates Na⁺ gradient

   1. Na⁺/K⁺-ATPase in basolateral membrane moves sodium from interior of epithelial cells surrounding lumen to interstitial fluid

   2. active transport of sodium out of cells creates concentration gradient favoring entry of sodium from lumen

2. Na⁺ gradient is used to remove solutes from filtrate

   1. sodium-dependent cotransporters in apical membrane use the Na⁺ gradient to remove ions and nutrients selectively from filtrate in lumen

   2. movement of sodium into cell, down its electrochemical gradient, provides means for moving other solutes against their gradient

3. removed substances diffuse into blood

   1. solutes that move from lumen into cell diffuse across basolateral membrane into interstitial fluid and then into nearby blood vessels

4. water moves into blood by osmosis

   1. water follows movement of solutes from proximal tubule into cell and then out of cell into blood vessels

Loop of Henle (40)

one of the major regions of the nephron; emerges from proximal tubule

establishes and maintains a strong osmotic gradient in the interstitial fluid surrounding this

osmolarity of the interstitial fluid increases as this descends into the medulla

• in most nephrons, this is short and barely enters medulla

functions as a countercurrent exchanger and multiplier:

• sets up and maintains a medullary osmotic gradient in interstitial fluid that surrounds it

• countercurrent flow of fluid is self-reinforcing

has 3 distinct regions:

1. descending limn

2. thin ascending limb

3. thick ascending limb

mammals that inhibit dry environments have longer loops; mammals in fresh water have shorter loops

Vasa recta (40)

water and salt that move out of the loop of Henle diffuse into here

network of blood vessels that runs along the loop

as a result, water and electrolytes that are reabsorbed are returned to bloodstream instead of being excreted in urine

Loop of Henle: descending limb (40)

one of the regions of loop of Henle

as fluid flows down this region, fluid inside loop loses water to tissue surrounding nephron

• this movement of water is passive, down its osmotic gradient

Loop of Henle: thin ascending limb (40)

one of the regions of loop of Henle

fluid inside nephron loses Na⁺ and Cl^- in this region:

• ions move passively along electrochemical gradients

Loop of Henle: thick ascending limb (40)

one of the regions of loop of Henle

near the renal cortex, osmolarity of surrounding interstitial fluid is low

additional Na⁺ and Cl^- are actively transported out of nephron in this region

Distal tubule (40)

one of the major regions of the nephron

• once filtrate has passed thru loop of Henle, it enters this region

reabsorbs ions and water from filtrate in a regulated manner

• one that helps maintain water and electrolyte balance according to body’s needs

fluid that enters this is always dilute

Collecting duct (40)

end of the nephron where the major regions empty into

may reabsorb more water to maintain homeostasis

in addition, urea moves from urine to the interstitial fluid at the base of the collecting duct and contributes to medullary osmotic gradient set up by the loop of Henle

in contrast, urine that leaves this region is dilute when individual is well hydrated but concentrated when the individual is dehydrated

Distal tubule and collecting duct (40)

activity of these regions of the nephron is highly regulated and altered in response to osmotic stress

amount of Na⁺, Cl^-, and water that’s reabsorbed in these regions varies with animal’s hydration

changes in these regions are controlled by hormones (signaling molecules in blood)

Antidiuretic hormone (ADH) (40)

important hormone in the regulation of water balance

• released after increase in osmolarity

• increases water reabsorption

makes collecting duct epithelium more permeable to water:

• triggers insertion of aquaporins into apical membrane; as a result, cells become much more permeable to water and large amounts of water a reabsorbed

• increases cell’s permeability to urea, which is reabsorbed into surrounding fluid; this helps create a concentration gradient favoring water reabsorption from filtrate

osmoreceptor cells in hypothalamus:

• monitor osmolarity of blood

• regulate the release of this hormone

Renin-angiotensin-aldosterone system (RAAS) (40)

vital hormone system that controls your blood pressure, blood volume, and fluid balance by managing sodium and water

responds to a decrease in blood volume

increases water reabsorption

Atrial natriuretic peptide (ANP) (40)

hormone made by the heart that lowers blood pressure, reduces salt, and decreases fluid volume

• acts as a natural opposite to RAAS

released in response to an increase in blood volume and pressure

inhibits release of renin

Aquaporins (40)

specialized channel proteins in cell membranes that rapidly transport water, facilitating osmoregulation in living cells

function:

• form pores that let water molecules pass thru in a single file at high speed

• allow water to move freely while blocking charged ions and protons to protect cellular energy systems

Excretory processes (40)

key functions of most excretory systems (in order):

1. filtration—filtering of body fluids

   1. based on size (large components of blood do not fit through pores in nephron)

2. reabsorption—reclaiming valuable solutes

3. secretion—adding nonessential solutes and wastes to filtrate

4. excretion—processed filtrate containing nitrogenous wastes is released from body

Cortex (40)

outer region of the kidney

contains most of the nephrons and is where blood filtration begins

houses the renal corpuscles, proximal tubes, and distal tubes, making it the primary site for filtration and much of reabsorption

this surrounds the medulla and receives a rich blood supply

Medulla (40)

inner region of the kidney

Contains the loops of Henle and collecting ducts that establish osmotic gradient needed for water reabsorption

allows the kid to produce concentrated urine and conserve water

the osmolarity increases deeper into this region, creating the gradient that drives water absorption

Animal nutrition (41)

4 processes needed to obtain energy from food:

• ingestion

• digestion

• absorption

• elimination

Ingestion (41)

process of bringing food into the digestive tract

Digestive tract (41)

also known as the alimentary canal, or gastrointestinal (GI) tract

series of connected chambers and tubes where digestion takes place

• various accessory glands secrete enzymes into here that digest food into particles small enough for efficient absorption

two general designs:

1. incomplete

2. complete

Incomplete digestive tracts (41)

a type of digestive tract design

have a single opening, the mouth, through which the animal both ingests food and eliminates wastes

the mouth opens into a chamber (gastrovascular cavity) where digestion takes place

e.g., Porifera and Cnidarians

Complete digestive tract (41)

a type of digestive tract design

have two openings—start at the mouth and end at the anus

the interior of this tube communicates directly w/ the external environment via these openings

advantages:

• different chemical and physical processes can be confined to different compartments so that they occur independently of each other and in sequence

Digestion: mouth (41)

digestion starts here

in the process of mechanical digestion, humans break down large chunks of food into smaller pieces by chewing action of teeth

• mechanical digestion increases surface area of food & mixes it into watery slurry so enzymes can do their job more easily (chemical digestion)

salivary glands secrete salivary amylase & mucus

cells in the tongue secrete lingual lipase

Salivary amylase (41)

enzymes responsible for carbohydrate digestion in the mouth

• secreted by salivary glands in mouth

cleaves bonds in starch to release dextrins (smaller carbohydrates of various lengths) as well as some disaccharides (e.g., maltose)

Salivary glands

glands in the mouth that secrete amylase and a slimy substance (mucus)

• water and mucus allow food to be swallowed

Lingual lipase (41)

cells in the tongue synthesize and secrete another salivary enzyme

• begins the digestion of lipids by breaking triglycerides (common form of fat) into diglycerides and fatty acids

this enzyme plays only a minor role in digestion, mostly once it’s been swallowed into stomach

Digestion: esophagus (41)

once food is swallowed, it enters this muscular tube which connects the mouth and stomach

in response to nerve signals, the smooth muscles in this tube contract and relax (peristalsis)

• these nerve signals are not the result of conscious choice, it’s a reflex

little if any digestion occurs here

Peristalsis (41)

wave of muscle contractions that propels food down the esophagus

it’s a reflex—automatic reaction to a stimulus stimulated by the act of swallowing)

Crop (41)

bird species have a prominent, widened segment of esophagus, called this

food can be stored and processed

• allows individuals to eat a large amount in a short time

• then they retreat to a safe location while digestion occurs

• in addition, some birds store food in this and then regurgitate it into the mouths of their young

Digestion: stomach (41)

tough, muscular pouch in the digestive tract, bracketed on both the superior and inferior ends by ringlike muscles (sphincters)

stores food and processes it into a liquid suspension

secretes gastric juice

• mixture of ingested food and gastric juice is called chyme

Sphincters (41)

muscular valve that can close off a tube, as in a blood vessel or a part of the digestive tract

brackets the stomach on both the superior and inferior ends by these ringlike muscles

• control the passage of material

these also prevent chyme (mix of ingested food & gastric juice) from entering the esophagus and regulate its entry into small intestine

Chyme (41)

a mixture of ingested food and gastric juice

formed in the stomach and moves into small intestine

Pepsin (41)

protein-digesting enzyme secreted in inactive form by chief cells in the stomach lining

Ruminant stomach (41)

stomach found in species called ruminants (e.g., cattle, sheep, goats, deer, antelope, giraffe, pronghorn)

stomach is specialized for digesting cellulose instead of proteins

has 4 chambers (in order):

1. rumen

2. reticulum

3. omasum

4. abomasum

animals do not produce the enzymes required to digest cellulose

• yet cellulose is the main carbohydrate in leaves, stems, and twigs

after partial digestion, these animals regurgitate portions of the material into its mouth (cud), and animal chews cud and re-swallows it

Avian gizzard (41)

prominent type of modified stomach found in birds

• particularly large and strong in birds that eat coarse foods

• interpreted as an adaptation that allow birds to ingest food quickly and digest later

birds don’t have teeth and can’t chew food into small pieces

• most species swallow sand and small stones that lodge here

• as this muscular sac contracts, food is pulverized by the grit

Digestion: small intestine (41)

long tube that’s folded into a compact space w/in the abdomen

in here, partially digested food mixes with secretions from the pancreas, liver, and gallbladder

when passage through this structure is complete, digestion is mostly done

• and most nutrients have been absorbed

epithelial lining of duodenum (first portion of this organ) produces several digestive enzymes

jejunum and ileum (portions of this organ) function mainly in absorption of nutrients and water

Pancreas (41)

connected to the small intestine by the pancreatic duct

produces proteases (protein-digesting enzyme) trypsin and chymotrypsin that are activated in the lumen of the duodenum

proteases aid in hydrolysis of peptide bonds

its solution is alkaline and neutralizes the acidic chyme

Pancreatic lipase (41)

completes digestion of lipids

• results in release of fatty acids and monoglycerides

Digesting lipids: bile and transport (41)

pancreatic secretions include digestive enzymes that act on fats as well as proteins and carbohydrates

pancreatic lipase completes digestion of lipids, which results in release of fatty acids and monoglycerides

fats tend to enter small intestine in large globules:

• must be broken by emulsification before pancreatic lipase can act on them

Bile (41)

made in the liver and stored in the gallbladder

aids in digestion and absorption of fats in the small intestine

• increases surface area for hydrophilic lipases to gain access to and digest fat molecules

destroys nonfunctional red blood cells

Gallbladder (41)

small pouch that stores bile from the liver and releases it as needed into small intestine during digestion of fats

Liver (41)

large, complex organ that performs many functions:

• storage of glycogen

• processing and conversion of food and wastes

• production of bile

Absorption: large intestine (41)

the primary function of this organ is to form feces by absorbing additional water and compacting the wastes that remain

includes:

• colon, cecum, and rectum

although the kidneys are responsible for maintaining water balance, water absorption here is important for keeping body well hydrated

Colon (41)

main section of the large intestine

feces are formed in here by absorbing additional water and compacting the wastes that remain

Rectum (41)

final part of the large intestine

feces are held here until they can be eliminated through the anus

Cecum (41)

blind sac at the anterior end of the large intestine

aids in the fermentation of plant material

• in some herbivores this is greatly enlarged b/c it contains symbiotic bacteria and protists that ferment cellulose

Appendix (41)

in humans, this narrow pouch emerges from the cecum

often has been described as vestigial b/c it doesn’t perform any obvious vital function

if it becomes inflamed, it can be surgically removed w/ no ill affects

contains immune system cells and appears to act as a haven for symbiotic microorganisms that inhabit colon

• plays a very minor role in immunity

Digestion (41)

the mechanical and chemical breakdown of food

Absorption (41)

the uptake of specific ions and molecules across the epithelium that lines the digestive tract

Elimination (41)

the process of removing waste from the animal’s digestive tract

Nutrients (41)

substances that an organism needs to remain alive

• animals get the chemical energy and building blocks they need from carbohydrates, proteins, and fats

food is any material that contains these substances

Essential nutrients (41)

although all nutrients are necessary for growth and survival of animals, these are nutrients are those that cannot be synthesized and must be obtained from the diet

4 classes of these nutrients:

1. amino acids

2. fatty acids

3. vitamins

4. minerals

Essential amino acids (40)

a class of essential nutrients

subunits of proteins obtained from the diet

amino acids that an animal cannot synthesize from simpler building blocks

the human diet requires 9 of these essential nutrients, which must be obtained from food

Essential fatty acids (41)

a class of essential nutrients

hydrocarbons obtained from the diet

fatty acids that an animal must obtain in its diet

• humans can synthesize all fatty acids except 2, which must be obtained from eating certain plants or fish

Vitamins (41)

a class of essential nutrients

organic, or carbon-containing, compounds that are vital for health but are required in only minute amounts

they’ve a variety of roles:

• several function as coenzymes in critical reactions

Minerals (41)

a class of essential nutrients

inorganic substances used as components of enzyme cofactors or structural materials

• some, like calcium and phosphorus, are needed in large quantities

• others, like iron and copper, are required in small amounts

this class include ions of electrolytes, which influence osmotic balance and required for normal membrane function

• sodium, potassium, and chloride are the major ions of electrolytes in the human body

Four feeding techniques (41)

1. suspension feeders

2. deposit feeders

3. fluid feeders

4. mass feeders

Suspension feeders (41)

a type of feeding technique/strategy

filter small organisms or bits of organic debris from water by means of cilia, mucus-lined “nets,” or other structures

e.g., sponges and tubeworms

Deposit feeders (41)

a type of feeding technique/strategy

swallow sediments and other types of deposited material rich in organic matter

e.g., earthworms and sea cucumbers

Fluid feeders (41)

a type of feeding technique/strategy

suck or lap up blood, nectar, or other fluids

e.g., mosquitoes, leeches, hummingbirds, etc.

Mass feeders (41)

a type of feeding technique/strategy

seize and manipulate chunks of food

majority of animals feed this way

• e.g., humans, carnivores, herbivores

Mouthparts as adaptations (41)

natural selection matched mouthpart structures to method of eating:

• most mammals chew and swallow distinct boluses—small, rounded mass of substance

• diversification of tooth shape allowed mammals to exploit range of foods

• snakes have mobile skull bones; can ingest large prey w/o chewing or biting off pieces

obtaining nutrients is fundamental; natural selection is strong for food capture